The Harman Kardon PM665 is a stereo integrated amplifier designed for high-fidelity audio reproduction. It serves as the central control unit for a home audio system, connecting various audio sources, processing their signals, and amplifying them to drive loudspeakers.
Function Description:
The PM665 integrates a preamplifier and a power amplifier into a single chassis, offering a comprehensive solution for audio enthusiasts. It features multiple input options for various audio sources, including turntables (both Moving Magnet and Moving Coil cartridges), tuners, CD players, and auxiliary video/audio components. The preamplifier section handles input selection, volume control, and tone adjustments, while the power amplifier section provides the necessary power to drive speakers.
A key feature is its dual RIAA phono equalization circuitry, which applies RIAA equalization in both open-loop and closed-loop signal paths, allowing for constant low-level negative feedback across the audio range. This design aims to improve accuracy and reduce distortion for phono playback.
The amplifier also includes a unique protection system designed to allow high instantaneous current delivery to speakers while safeguarding the amplifier from short circuits or damaged components. This system is engineered not to limit amplifier output voltage or current during music reproduction, thus preserving sound quality.
For recording purposes, the PM665 offers flexible tape monitor and tape out selectors, enabling recording from any selected source to one or two tape decks, as well as dubbing between two tape decks. This allows users to record broadcasts, vinyl, or other sources, and to create copies of tapes.
Important Technical Specifications:
- Power Output (RMS): 100 watts per channel into 8 Ohms, 20-20,000Hz, at less than 0.08% THD. This indicates a robust power delivery capable of driving a wide range of speakers with clarity.
- HCC (High Instantaneous Current Capability): 60A. This high current capability is crucial for handling the dynamic, low-impedance demands of modern loudspeakers, preventing dynamic range compression and increased distortion.
- Power Bandwidth: 10Hz to 100,000Hz (at half rated output into 8 Ohms). An exceptionally wide bandwidth contributes to improved transient accuracy and phase linearity.
- Frequency Response: 0.2Hz to 150,000Hz (+0, -3dB). This broad frequency response ensures that the amplifier can reproduce the full spectrum of audible sound and beyond.
- Damping Factor: >65. A high damping factor indicates good control over speaker cone movement, leading to tighter bass and improved transient response.
- Signal-to-Noise Ratio (IHF-A WTD, reference 1W output):
- Phono (MM): 77dB
- Phono (MC): 75dB
- Tuner, CD, Video/AUX, Tape: 78dB
- Main-in: 92dB
These figures indicate a low noise floor, ensuring that the music signal is reproduced with minimal interference.
- Input Sensitivity/Impedance:
- Phono (MM): 2.2mV/47k Ohms and 125pF
- Phono (MC): 120μV/56 Ohms
- Tuner, CD, Video/AUX, Tape: 135mV/22k Ohms
- Main-in: 0.8V/22k Ohms
These specifications ensure compatibility with a wide range of audio sources.
- Phono Overload: MM: 220mV, MC: 12mV. These values indicate the maximum input level the phono stage can handle without distortion.
- Tone Control Characteristics:
- Bass Turnover Frequency: 200Hz/400Hz
- Treble Turnover Frequency: 2kHz/6kHz
These adjustable turnover frequencies allow for precise tailoring of the bass and treble response.
- Filters:
- Subsonic: 15Hz, 6dB/Octave
- High Cut: 6kHz, 6dB/Octave
These filters help to remove unwanted low-frequency rumble (from turntables) or high-frequency noise (like disc scratches or tape hiss).
- Bass Contour: Boost (at 50Hz): +10dB, Phase Shift: <5° (300-20,000Hz). This unique feature provides a bass boost with phase correction for natural sound, especially beneficial for smaller speakers.
- Dimensions (W x H x D): 17-1/2" x 5-5/16" x 15-11/16" (443 x 134 x 398 mm).
- Weight: 29lbs. 12oz. (13.5kg).
- Power Supply: AC 120V, 60Hz.
- Power Consumption: 550W.
Usage Features:
- Multiple Inputs: Dedicated inputs for Phono (MM and MC), Tuner, CD, Video/AUX, and two Tape decks provide extensive connectivity options.
- Speaker Selection: Allows connection and selection of up to two pairs of speakers (Speakers 1, Speakers 2, or both 1+2), or headphones only. Minimum speaker impedance is 4 Ohms for a single pair, or 4 Ohms net impedance for two pairs.
- Tone Controls: Independent Bass and Treble control knobs with selectable turnover frequencies (200Hz/400Hz for bass, 2kHz/6kHz for treble) allow users to fine-tune the sound to their preference or room acoustics. A "Tone Defeat" switch bypasses these circuits for a flat frequency response.
- Balance Control: Adjusts the relative output level between the left and right channels.
- Capacitance Trim Selector: This feature, with settings for "normal," "+100pF," "+200pF," and "+300pF," allows for precise impedance matching with Moving Magnet phono cartridges, optimizing frequency response.
- Cartridge Selector (Phono 2): Switches between MM (Moving Magnet) and MC (Moving Coil) settings for the Phono 2 input, accommodating different turntable cartridge types.
- Pre-out/Main-in Switch: This switch allows the preamplifier and power amplifier sections to be used independently. In the "integrated" position, they are connected internally. In the "separate" position, external preamplifiers or power amplifiers can be connected via the rear panel jacks.
- Bass Contour Switch: Activates a unique low-frequency equalization circuit designed to provide full, natural sound, particularly beneficial for small speakers, and can serve as an alternative to conventional loudness compensation.
- Filter Switches: Subsonic filter reduces unwanted low-frequency rumble, and High Cut filter reduces high-frequency noise.
- Mode Switch: Combines left and right channels to create a mono signal.
- Mute Switch: Attenuates the signal level by -20dB, useful for temporary sound reduction.
- AC Convenience Receptacles: Three receptacles (two switched, one unswitched) on the rear panel provide power for other audio components, with a combined capacity of 200 watts for switched and 200 watts for unswitched.
Maintenance Features:
- Protection Circuitry: The unit incorporates a protection circuit that mutes the output during startup (indicated by a blinking power indicator) and safeguards against potential damage.
- Fuse Replacement: The manual advises against user replacement of fuses and recommends consulting an authorized Harman Kardon service station if a fuse blows.
- Cleaning: Recommends wiping the unit with a soft dry cloth, or a soft cloth dampened with mild soapy water, followed by a dry cloth. Warns against using volatile agents or insecticides.
- Troubleshooting Checklist: The owner's manual includes a detailed troubleshooting guide to help users diagnose and resolve common operational issues before seeking professional service. This covers problems like no power, no sound, unbalanced sound, tone control malfunction, reversed channels, and hum/buzz from a turntable.
- Warranty Information: The manual refers to an enclosed warranty policy, typically covering the unit for two years from the date of purchase, emphasizing the importance of retaining the bill of sale.
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